Rheological sand bed generates non‐rebounding particles

Abstract

Wind‐blown sand movements induce desertification and cause various environmental problems. This study investigates the rebound probability of sand particles during sand transport. The widely used rebound probability models are essentially empirical and the mechanism that generates non‐rebounding particles remains unclear. By tracking the grain–bed collision process of impact particles in steady‐state sand flows, it was observed that non‐rebounding particles undergo repetitive collisional momentum losses within the rheological layer of the sand bed. Therefore, rebound probability models based on the incident velocity and angle cannot realistically describe rebound probability. Furthermore, the rheological sand bed produces numerous rebound particles with a coefficient of restitution above 1.0, converting the normal distribution of the coefficient of restitution into a lognormal distribution pattern with considerably larger variances. The new insights into aeolian rebounds gained through this study are expected to reduce the uncertainties in sand flux predictions.